Fix cases where Connection Establishment Timed Out is incorrectly logged (1.6.x) (SimplePool)

[miklish]

PR: #2178

In SimpleUndertowConnectionMaker, it is possible that a connection failure can be mis-logged as a connection timeout.

This fix corrects this and also adds more details to the logs about the cause of connection failures.

NOTE:

• Please merge PR Use Generic Name for SimplePool Connection Threads (1.6.x) #2090 before this.
  because:
• This issue's PR contains the updated code from PR Use Generic Name for SimplePool Connection Threads (1.6.x) #2090.